Prosthetic leg with weight responsive knee lock

ABSTRACT

A knee structure for a prosthetic limb, which allows the shin portion to pivot with respect to the thigh portion about an axle and has a brake band around the axle with novel means for causing the brake band to tighten around the axle, when the wearer places weight on the limb, to allow the knee to lock at any angular position. The brake automatically releases when the weight is lifted off the limb.

Hittite States Patent 91 Kolman 1 Apr. 3, 1973 I [75] Inventor:

i541 PROSTHETIC LEG WITH WEIGHT RESPONSIVE KNEE LOCK John L. Kolman,Whittier, Calif.

[73] Assignee: United States Manufacturing Company, Glendale, Calif.

[22] Filed: Apr. 30, 1971 [21] Appl. No.2 134,262

[52] U.S. Cl ..3/27, 3/29 [51] Int. Cl ..A6lf 1/04, A61f 1/08 [58] Fieldof Search ..3/2229, 2

[56] References Cited UNITED STATES PATENTS 1,283,093 10/1918 Critchley..3/24 3,172,127 3/1965 Tolotti ..3/27

2,645,779 7/1953 Barghausen ..3/28

OTHER PUBLICATIONS Orthopaedic Appliances Atlas, Vol. 2, ArtificialLimbs, by J. W. Edwards, Ann Arbor, Mich, 1960, pages 197 and 198 (FIG.592).

Primary Examiner-Richard A. Gaudet Assistant Examiner-Ronald L. FrinksAttorney-Dominick Nardelli [57] ABSTRACT A knee structure for aprosthetic limb, which allows the shin portion to pivot with respect tothe thigh portion about an axle and has a brake band around the axlewith novel means for causing the brake band to tighten around the axle,when the wearer places weight on the limb, to allow the knee to lock atany angular position. The brake automatically releases when the weightis lifted off the limb.

7 Claims, 7 Drawing Figures PATENTEDAPR 3 ms SHEET 1 OF 2 INVENTOR. JohnL K01 man 4/1 0 rue PAIENTEDAPM I975 3,723,997

SHEET 2 [)F 2 INVENTOR.

Ja/m L Aa/ma zW/arney PROSTHETIC LEG WITH WEIGHT RESPONSIVE KNEE LOCKFIELD OF THE INVENTION The present invention relates to a prostheticlimb and, more particularly, to the knee structure thereof with a meansfor braking.

BACKGROUND OF THE INVENTION Prosthetic or artificial limbs have beendesigned many ways and each way is calculated to simulate more closelythe motion of a natural limb. However, at times this appears to be animpossibility because of the many functions our Great Creator compactedwithin a rela tively small package. Therefore, man can only hope toapproach the function of the natural limb. Up to now, a prosthetic leghad a knee structure which locked when the leg was straight so that theknee would not give way from under the wearer. If the wearer desired tolock the knee when the leg was bent, he had to use his hands to apply alock to the knee assembly in the bend position.

OBJECTS OF THE INVENTION An object of this invention is to provide anovel pivotal structure for a prosthetic limb which can be locked in anyangular position.

Another object of this invention is to provide a knee structure for aprosthetic leg having a means for locking the knee whenever weight issupported by the prosthetic leg.

Another object of this invention is to provide a novel knee structurethat is simple, durable, economical and more closely simulates, infunction, a natural knee.

These and other objects and features of the invention will becomeapparent after studying the following description and the accompanyingdrawings which describe and illustrate the preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a small scale pictorial viewof the novel prosthetic leg.

FIG. 2 is a side elevation in section taken on the center line of theknee structure of the novel leg shown in FIG. 1.

FIG. 3 is also a side elevation in section taken on one side of thecenter line showing the knee structure with the knee slightly bent.

FIG. 4 is a plan section taken substantially on line 4-4 in thedirection of the arrows shown in FIG. 2.

FIG. 5 is a section taken on line 5-5 in the direction of the arrowsshown in FIG. 2 showing only the brake portion.

FIG. 6 is a pictorial view of the brake band employed in the knee.

FIG. 7 is a pictorial view of the brake drum.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 shows a prosthetic legincorporating this invention and there is shown a thigh portion 11 and ashin portion 12 which pivot relative to each other about an axle orshaft 13. The shaft 13 is disposed in the shin portion through bores,such as bore 14 (FIG. 4), formed within one of the respective two bosses15. The

shin portion 12 has a well 16 (FIG. 2) extending down through the topthereof an bosses 15 are disposed on opposite sides of the well 16. Theshaft 13 is suitably keyed to the bosses 15 and, in turn, the shinportion.

The thigh portion 11 is attached to the shaft 13 through two cranks orlinks (21) placed on opposite sides of the thigh portion 11, as shown inFIG. 4. Each link 21 has bores 22 and 23 formed at the respective ends.Through bores 23 on both links 21 is disposed a rod 24 and is suitablykeyed to the links 21. Through bores 22 of both levers 21 passes theshaft 13, and between the wall of the bore 22 and shaft 13 are disposedbronze bushings 26 which are suitably fixed to the respective levers 21.Since the shaft 13 is preferably made of stainless steel, thebronze-stainless steel mating surfaces form a bearing. To change thedrag on this bearing, each bushing 26 has axially parallel slots 27, anda brass band 28 with tightening screw and bolt 29 surround each bushing26 over the portion extending inward from the links 21. Thus, bytightening the screws and bolts 29, the bushings 26 clamp down harder onthe shaft 13, increasing the drag. This feature is standard in the artto provide a knee swing to the feel of the wearer. Rod 24 is alsopreferably stainless steel and it passes through two aligned bores 31 inthe thigh portion 11, with suitable plastic bushings 32 therebetween toprovide a bearing. Between the bores 31 and in the thigh portion acavity 35 (FIG. 2) is formed at the lower end to provide two opposingmembers 35a, which cavity is preferably accessible from the rear whereinis provided an opening 36. Bores 31 are in members 35a. In addition, thethigh portion has two aligned holes 37 (FIG. 4) also situated onopposite sides of the cavity 35, through which holes 37 pass the shaft13 and bronze bushings 26. These holes 37 are much larger than the itemtherein disposed for reasons that will become apparent hereinafter.Aligned bores 41 are also formed in the thigh portion to accommodate adowel 24 to which is engaged a check lever 43, the lower end of whichengages a suitable member (not shown), as is standard in the art tocheck or prevent the forward swing of the shin portion 12.

Within the cavity 35 is disposed the novel means for locking the knee inany angular position. The means, in the preferred embodiment, comprisesa brake band 51 surrounding a brake drum 52 on the shaft 13, as shown inFIG. 2. The brake band 51 and 'drum 52 are preferably made of nylon. Thedrum 52 is cylindrical in shape, as shown in FIG. 7, and is locked tothe shaft 13 by a set screw 53 (FIG. 2). The brake band 51 is generallyU-shaped, as shown in FIG. 6, wherein one side 51a of the band is muchlarger than the other 51b and the one side 51a has a bore 54 throughwhich passes the rod 24. The band 51 is locked to the rod by a set screw53a. The brake band 51 is tightened whenever a brake lever 55 is pusheddown. This function is possible because the brake lever 55 engages ascrew 56 under its head, which screw is disposed substantiallyvertically, and loosely passes through a hole 57 in the larger side 51aand engages suitable nut 58 imbedded in a hole 59 in the other side 51bof the band 51. The brake lever 55 pivots about a fulcrum 61 on thebrake band 51. The rearwardly disposed end or end of the lever 55disposed over dowel 42 bears against an upper wall 35a of the cavity 35,as shown in FIGS. 2 and 3.

Two compression springs 62 (FIG. 5) acting between opposite sides 51aand 51b of the brake band 51 ensure that the band and drum are free whenthe lever 55 is not depressed.

The brake is applied whenever the wearer places weight on the prostheticleg to transfer force from one portion to the other. When weight isbeing supported the weight is transmitted by the thigh portion to theshin portion 12 through bushings 32 around rod 24 and through the lever55, since it is in contact with the upper wall 35a of the cavity 35.This bearing force on bushings 32 causes both links 21 to tend to rotateabout the shaft 13, since the forward ends of the ends 21 are beingpressed down. The thigh portion moves downward slightly causing thebrake lever 55 to pivot about the fulcrum 61, lifting the front end ofthe lever 55 and the screw 56. This motion to the brake lever 55 can beapplied by the wearer when the knee is in any angular position, as shownin FIG. 3, to allow the wearer to lock the knee when, for example, inthe half knee-bend position. When the wearer lifts his leg, as whenwalking, the knee is free to bend or swing, since the thigh portion 11lifts up off lever 55.

Although one embodiment of the invention has been shown and described,the invention is not limited thereto but includes all embodiments withinthe scope of the claims.

I claim:

1. A prosthetic leg comprising:

a thigh portion having a cavity formed at the lower end thereof withopposing walls a shin portion having a well at the upper end withinwhich well the lower end of the thigh portion is free to pivot a shaftfixed to said shin portion at the upper end thereof and across saidwall,

a rod passing through said opposing wall of said thigh portion, and

a pair of links engaging said rod and said shaft at their respectiveends,

a brake band disposed within said cavity, around said shaft and affixedto said rod, and

a lever member disposed within said cavity engaging said brake band andsaid thigh portion so that the brake band tightens around said shaftwhen the thigh portion bears down upon said lever member.

2. The leg of claim 1 wherein:

said rod is disposed on one side of said shaft and parallel thereto,

said brake band is U-shaped and has the upper side thereof fixed to saidrod,

a bolt passes through both sides of the band and is free with respect tothe upper side and fixed to the underside,

said lever member engages the upper end of said bolt,

a fulcrum is on the upper side of said brake band on which said levermember pivots,

said lever member bearing against the upper wall of said cavity at apoint thereof disposed on the side of said shaft opposite said rod.

3. A prosthetic leg comprising:

a thigh portion having a pair of opposing members depending from thelower end thereof,

a shin portion having a well at the upper end for receiving saidmembers,

said pair of members having at least one pair of aligned holes,

a rod disposed snugly within said pair of aligned holes, 1

a shaft disposed at the upper end of said shin portion and across saidwell,

a link connecting said rod to said shaft and being joumaled on saidshaft,

a brake band disposed between said pair of members and around said shaftand having one end thereof engaging said rod, I

a bolt fixed to the other end of said band, which slides through anopening in said one end of said brake band,

afulcrum,

a lever engaging said bolt and said thigh portion so that when weight isbeing supported by said leg said link rotates downward about such shaft,causing said thigh portions to drop slightly, pivoting said lever aboutsaid fulcrum to cause said bolt to slide with respect to said opening insaid one end, causing the brake band to tighten around the shaft.

4. The leg of claim 3 wherein:

another link is provided connecting said rod to said shaft with saidbrake band disposed between the levers,

said other link is journalled on said shaft,

said rod is substantially disposed in front of said shaft when the legis in the straight portion,

said lever is disposed so that one end extends rearward to engage saidthigh portion so that weight is transmitted through the spaced areas tosaid shin portion.

5. The leg of claim 3 wherein:

said one end of said brake band is disposed over the other end and has abore through which said rod passes,

said lever engages said bolt by the forward end of the lever,

said fulcrum if formed on said brake band on the upper side thereof.

6. A pivotal mechanism for a prosthetic limb com prising:

a first portion with a cavity formed at one end thereof,

a second portion with a well formed at one end to allow said one end ofsaid first portion to pivot freely therein,

a shaft fixed to said second portion across said well,

a rod passing through and in joumaled relationship with the opposingwalls of said cavity,

means for allowing said rod to rotate about and parallel to said shaft,

a brake band disposed around said shaft and within said cavity andhaving one end engaging said rod and the other end having contact withsaid first portion so that said brake band tightens around said shaftwhen said first portion bears toward said second portion.

7. The mechanism of claim 6 wherein:

said one end of said brake band has a hole formed therethrough,

a link is disposed through said hole and is connected to said other end,

a fulcrum is formed on said one end a lever is connected at one end tosaid pin and disposed to pivot about said fulcrom and has its other endin contact with said first portion.

1. A prosthetic leg comprising: a thigh portion having a cavity formedat the lower end thereof with opposing walls a shin portion having awell at the upper end within which well the lower end of the thighportion is free to pivot a shaft fixed to said shin portion at the upperend thereof and across said wall, a rod passing through said opposingwall of said thigh portion, and a pair of links engaging said rod andsaid shaft at their respective ends, a brake band disposed within saidcavity, around said shaft and affixed to said rod, and a lever memberdisposed within said cavity engaging said brake band and said thighportion so that the brake band tightens around said shaft when the thighportion bears down upon said lever member.
 2. The leg of claim 1wherein: said rod is disposed on one side of said shaft and parallelthereto, said brake band is U-shaped and has the upper side thereoffixed to said rod, a bolt passes through both sides of the band and isfree with respect to the upper side and fixed to the underside, saidlever member engages the upper end of said bolt, a fulcrum is on theupper side of said brake band on which said lever member pivots, saidlever member bearing against the upper wall of said cavity at a pointthereof disposed on the side of said shaft opposite said rod.
 3. Aprosthetic leg comprising: a thigh portion having a pair of opposingmembers depending from the lower end thereof, a shin portion having awell at the upper end for receiving said members, said pair of membershaving at least one pair of aligned holes, a rod disposed snugly withinsaid pair of aligned holes, a shaft disposed at the upper end of saidshin portion and across said well, a link connecting said rod to saidshaft and being journaled on said shaft, a brake band disposed betweensaid pair of members and around said shaft and having one end thereofengaging said rod, a bolt fixed to the other end of said band, whichslides through an opening in said one end of said brake band, a fulcrum,a lever engaging said bolt and said thigh portion so that when weight isbeing supported by said leg said link rotates downward about such shaft,causing said thigh portions to drop slightly, pivoting said lever aboutsaid fulcrum to cause said bolt to slide with respect to said opening insaid one end, causing the brake band to tighten around the shaft.
 4. Theleg of claim 3 wherein: another link is provided connecting said rod tosaid shaft with said brake band disposed between the levers, said otherlink is journalled on said shaft, said rod is substantially disposed infront of said shaft when the leg is in the straight portion, said leveris disposed so that one end extends rearward to engage said thighportion so that weight is transmitted through the spaced areas to saidshin portion.
 5. The leg of claim 3 wherein: said one end of said brakeband is disposed over the other end and has a bore through which saidrod passes, said lever engages said bolt by the forward end of thelever, said fulcrum if formed on said brake band on the upper sidethereof.
 6. A pivotal mechanism for a prosthetic limb comprising: afirst portion with a cavity formed at one end thereof, a second portionwith a well formed at one end to allow said one end of said firstportion to pivot freely therein, a shaft fixed to said second portionacross said well, a rod passing through and in journaled relationshipwith the opposing walls of said cavity, means for allowing said rod torotate about and parallel to said shaft, a brake band disposed aroundsaid shaft and within said cavity and having one end engaging said rodand the other end having contact with said first portion so that saidbrake band tightens around said shaft when said first portion bearstoward said second portion.
 7. The mechanism of claim 6 wherein: saidone end of said brake band has a hole formed therethrough, a link isdisposed through said hole and is connected to said other end, a fulcrumis formed on said one end a lever is connected at one end to said pinand disposed to pivot about said fulcrom and has its other end incontact with said first portion.